Nanoscale physics
Formation of gold nanostructures on MoS2 surface modified 
by polyvinylpyrrolidone
Borodinova T.I.1, Styopkin V.I.2, Vasko A.A.2, Cherepanov V.V.2, 
Marchenko А.A.2
1 F. D. Ovcharenko Institute of Biocolloid Chemistry, National Academy of Science, Kyiv, Ukraine
E-mail: borodinova@ua.fm
2 Institute of Physics, National Academy of Science, Kyiv, Ukraine

Gold nanoprisms can enhance Raman signals of analyte. In our earlier study [1] the intensity of some peaks of Raman spectra of rhodamine R6G dye molecules (4 μM) is amplified 104 times when the Raman signal is excited with laser beam focused on an apex of gold nanoprism. We propose the creation of a surface-enhanced Raman scattering (SERS)-active substrate by synthesizing gold nanoprisms/nanoparticles on a modified by polyvinylpyrrolidone (PVP) MoS2 surface. 
The composite MoS2 / PVP / Au nanostructures can be obtained in two steps: (i) the first, adsorption (temperature T=80 °C, time t=48 h) of polyvinylpyrrolidone (Mw=29 kDa) from alcohol solution 45 mM on surface freshly cleaved MoS2 sheets, (ii) and then the synthesis of gold nanoparticles by the polyol method on this substrate. The formation of Au nanostructures on the MoS2 / PVP was carried out in the growth medium containing mixture of glycerol, ethylene glycol, ethanol (7:7:6, v:v) and 1 mM HAuCl4 at temperature 80 °C during 48 hours. 
 Triangular, hexagonal and dendrite-like nanoprisms were detected by method of scanning electron microscopy on the MoS2/PVP interface. AFM studies have shown that the surface of those prisms is free from the layer of PVP.  

1. Borodinova Т.I., Кravets V.G., Romanyuk V.R. Gold Nanocrystals as a Substrate for Micro Raman Spectroscopy // J. Nano- Electron. Phys. – 2012. – 4, No 2, 02039 (7pp).